412da2789a
Stacked on #1304, which this targets; it retargets to `main` once #1304 merges. Together they replace #1303. ## What a v2 client gets now **`idle` at a turn's result,** also when v1 holds the turn's answer for the background subagents it spawned (`Turn.deferredSettle`). - The subagents' output and permission requests arrive while the session is idle. The draft allows that: background activity may send updates while idle, and they don't change the state. - A background request while idle no longer shows `requires_action`, which the draft reserves for foreground work. - The hold itself is unchanged. It now only delays v1's answer, with no v2 branch in the hold logic. **Model cycles that Claude Code starts on its own** are foreground work: the follow-up after a background subagent or command finished, or its answer to a message from another session. - A cycle reports `running` before its first output, `requires_action` while it waits, then `idle` with its own stop reason, usage and `_meta.quota`. - An error result gives `idle` with the `error` stop reason, and a cancel gives `idle cancelled`. - Before this, such a cycle streamed while v2 said `idle`. **Take-overs:** a prompt that Claude Code takes in during a cycle takes it over, with no new `running` and no `idle` in between. So do a steer that resumes a held turn, and the continuation of an accepted clear-context plan. In both, the final `idle` carries the turn's usage, not just the last cycle's. v1 and AIR clients are unchanged. ## How All of this builds on #1304's `ForegroundEvents`: - **A turn's work ends at its result:** `endForeground` in the defer branch of `settleOrDefer`, and where the steer idle lane re-applies a hold. - **A cycle starts** (`startAutonomousCycle`) at model output of the main conversation while no work runs. - Subagent output doesn't count. - Without command lifecycles, output while a prompt is queued stays that prompt's, since its output can come before its echo. With lifecycles (`msg_lifecycle_v1`), a prompt Claude Code hasn't started has no output yet, so a cycle starts. This narrows the gap that #1303 left. - **A cycle ends:** - at a result no turn took, except a placeholder result (`num_turns: 0`); - with `cancelled` at the diagnostic of an ExitPlanMode answer, as a turn does, unless a held turn continues the accepted plan; - at an SDK `idle` that no earlier result owes; - when the stream ends or fails; - before `session/close` answers. - **Starting work while a request is open** reports `requires_action` at once. - **The cycle's stop reason** comes from its result, as for a turn (`autonomousCycleEnd`). Its `_meta.quota` uses the same builder as a turn's (`quotaMeta`, extracted from `turnQuotaMeta`). ## Checks - `npm run check`, `npm run build` and all 2756 tests pass. No golden file changes against #1304: no recorded scenario has a held turn or output while no turn is active. - New tests: - **14 v2 tests:** #1303's eleven, plus a held turn reporting `idle` at its result with its follow-up as a cycle and a background request while idle, output before a queued prompt that Claude Code reports it hasn't started, and `session/close` during a cycle; - **agent:** a steer resuming a held turn's work; the follow-up that ExitPlanMode's "keep planning" interrupts ending `cancelled`; the clear-context continuation taking the cycle over, with the turn's usage; - **turn events:** work that starts while a request is open waits at once. - I made 20 mutations, one per rule above, and each failed a test. The take-overs for a steer and for the clear-context restart first survived, since a cycle stood in for the turn with the same states. The tests now check the usage of the final `idle` too. ## Not covered - No recorded scenario has such a cycle. The start signal (the first main-thread output) is chosen from the agent's side, not confirmed against a live CLI. - After a cancel, the agent drops main-thread output until the next prompt (`session.cancelled` stays set). So a follow-up that Claude Code runs after a cancel is still lost, for v1 and v2. That predates this PR, and I'll fix it separately.
ACP adapter for the Claude Agent SDK
Use Claude Agent SDK from ACP-compatible clients!
This tool implements an ACP agent by using the official Claude Agent SDK, supporting:
- Context @-mentions
- Images
- Tool calls (with permission requests)
- Compact file changes through the negotiated AIR diff patch extension
- Following
- Edit review
- TODO lists
- Nested subagent transcripts
- Interactive (and background) terminals
- Custom Slash commands
- Client MCP servers
/mcpin the chat: the MCP server status as a list. The adapter runs/mcp reconnect,/mcp enable, and/mcp disablethrough the SDK control API, because Claude Code refuses them in SDK mode. A reconnect of an ACP server that needs authentication starts MCP OAuth through URL elicitation- Session-scoped long-running goals for AIR through the goal extension under
_meta.jetbrains.air.goal - Structured errors, recovery, and warnings through the opt-in session failure extension
- Concrete model and effort defaults through the opt-in recommended config value extension
- Tool permission presentation, editable choices, and durable effects through the permission extension
- One fact per field in every tool call report, as the ACP tool call contract defines
- All AIR extensions, capabilities, and
_metakeys: AIR extensions
Learn more about the Agent Client Protocol.
To try changes that have landed on main but are not released yet, install from the
preview channel — every push to main publishes one. See
docs/RELEASES.md.
npm install @agentclientprotocol/claude-agent-acp@preview
Subagent sessions
Subagents are exposed only after bilateral capability negotiation. Until the released ACP SDKs
preserve the draft clientCapabilities.subagents field, a supporting client may advertise
nativeSubagentSessions in _meta.jetbrains.air.capabilities; the adapter mirrors the capability
in its initialize response. The canonical field remains supported and takes precedence once it is
available. Without either client signal, Agent/Task lifecycle keeps its legacy ordinary ACP
tool-call representation and child interactions stay on the root session. Clients that use the
historical _meta["subagent-transcript"] capability or forwardSubagentText session option retain
the flattened child transcript behavior. See AIR extensions.
Contribution Policy
This project does not require a Contributor License Agreement (CLA). Instead, contributions are accepted under the following terms:
By contributing to this project, you agree that your contributions will be licensed under the Apache License, Version 2.0. You affirm that you have the legal right to submit your work, that you are not including code you do not have rights to, and that you understand contributions are made without requiring a Contributor License Agreement (CLA).